Synthesis and structural studies of heteroleptic complexes of ytterbium(III) involving aryloxy- or alkoxy- and cyclopentadienyl ligands

Abstract

Treatment of tris-cyclopentadienyl-ytterbium in thf with one equivalent of 2,6-di( tert-butyl)phenol, N, N-dimethyl-2-aminoethanol or N, N-diethyl-2-aminoethanol resulted in substitution of one cyclopentadienyl ligand and formation of [YbCp 2(O-C 6H 3 t Bu-2,6)(thf)] ( 1), [{YbCp 2(μ-OCH 2CH 2NMe 2)} 2] ( 2) or [{YbCp 2(μ-OCH 2CH 2NEt 2)} 2] · (thf) 2 ( 3), respectively. All compounds were characterised by spectroscopic and X-ray crystallographic techniques, the latter two also being studied by variable temperature 1H NMR spectroscopy. Compound ( 1) is mononuclear with the Yb centre bound by two η 5-cyclopentadienyl ligands one O-bound thf and an O-bound phenoxy ligand. Compounds ( 2) and ( 3) are centrosymmetric dimers with the Yb centre bound by two η 5-cyclopentadienyl ligands, while the bidentate ligands chelate the metal centre and also bridge to the adjacent Yb through the alkoxy oxygen atom. Variable temperature 1H NMR studies on compounds ( 2) and ( 3) show a solution-state equilibrium between the dimeric solid-state structure and one with the nitrogen atoms non-bound to Yb.